The invention relates to an oil circuit for a working machine, especially an internal combustion engine.
Such oil circuits in the state of the art are at least partially integrated into the engine block of an internal combustion engine. Especially the oil pan which forms a reservoir for the lubricant oil is provided in the bottom part of the engine block. It is directly connected with the crankcase, and the lubricant oil collects in it so as to be returned by means of a pump back to the lubrication points of the internal combustion engine.
An effort is being made to keep the manufacturing cost involved in the oil circuit as low as possible. This can be achieved by integrating the components necessary for the oil circuit into the motor block. For example, it is proposed in DE 198 33 974 A1 (=GB 2,327,625) to design the oil filter as a flat filter and insert it into a receiver provided for it in the oil pan. Another possibility is to integrate the pump of the oil reservoir into the oil pan, as proposed in DE 196 44 645 A1 (=EP 838,577).
These measures are capable of reducing the design cost of the internal combustion engine and thus reducing the manufacturing and assembling costs. However, the operating costs cannot be reduced by that. All that can be done is to strive for long maintenance intervals through the quality of the oil and by extending the useful life of the filter. The maintenance itself presents difficulties; the used filter elements have to be removed and the old oil drained out. There is danger of contaminating the environment with accidentally lost oil. Also, the used-up filter elements as well as the old oil must be disposed of properly.
It is therefore an object of the invention to provide an oil circuit which in addition to low manufacturing and installation costs will entail low cost of operation.
It is also an object of the invention to provide an oil circuit which will permit easy as well as reliable maintenance.
These and other objects are achieved in accordance with the invention by providing an oil circuit for a working machine comprising an oil reservoir and a conduit system for delivering oil to lubrication points of the machine, wherein the reservoir is integrated into an insert unit which is replaceably disposed in a receptacle and which forms a part of the oil circuit.
The oil circuit according to the invention is comprised of a circulatory system to deliver oil to the lubrication points of the machine and a reservoir for the oil from which the circulatory system is supplied. Also, any oil that is not needed for circulation flows into this reservoir. The oil circuit according to the invention is characterized in that this reservoir is part of an insert unit which is placed in a receptacle in the working machine. The insert unit thus forms part of the oil circuit and can easily be replaced with a new one in order to change the lubricant oil. Receptacles for such insert units can be provided, for example, on the engine which contains the oil circuit. The exchange can then be simply performed by releasing the fastening of the insert unit that is connected to the receptacle.
The insert unit can be attached to the engine or the oil circuit, the receptacle being comprised of, for example, a bayonet connector, or according to another embodiment of the invention an installation opening can be provided which can be opened to install the insert unit and then closed. Alternatively, a drawer-like receptacle can be provided for receiving the insert unit; for example, a receptacle which facilitates handling when the insert unit is exchanged. The cover of the installation opening furthermore leads to greater reliability of the oil circuit in operation because an additional seal can be produced by the cover.
In one practical embodiment of the invention, the insert unit and the conduit system of the oil circuit have connectors which can be joined together when the insert unit is installed. This can be performed by a separate attachment of the conduit system (tubing, for example), or the connectors may be integrated into the insert unit such that the insert unit is automatically connected to the circulation system by its insertion into the receptacle. As an alternative to the connectors, the insert unit can also be constructed with an open structure, so that the connectors of the conduit system can extend into it. The insert unit itself then has no connectors.
An especially reliable variant of the invention as regards maintenance is obtained when the connectors have valves which close if the insert unit becomes separated from the oil circuit. This can be accomplished manually or automatically through a corresponding linking of the valves to the connectors. Advantageously, when the insert unit is separated from the oil circuit, all openings through which the oil could pass into the environment become closed. Replacement of the insert unit is thereby especially secure and can be performed even by untrained personnel.
The removed insert unit is by itself a sealed system and can be discarded as a whole to dispose of the old oil. In a special application of the invention the insert unit is taken back with the old oil by the oil producer, who replaces the old oil with fresh oil and then can resell the refurbished insert unit again. This kind of embodiment permits recycling the old oil and multiple use of the insert units, similar to the principle of the returnable bottle.
In one preferred embodiment of the invention, the insert unit can be housed in the cylinder head of an internal combustion engine. In general, this area of the motor block is quite easily accessible so that the insert unit can be easily replaced. Since the insert unit is simultaneously the container for the lubricating oil and the cylinder head is generally located in the top part of the internal combustion engine, the oil must be pumped into the insert unit by the oil circulation pump provided for the lubricating oil circuit. For this purpose a lubricant oil collection point can be provided in the lowest part of the lubricating oil circuit, from where the oil circulation pump pumps the lubricating oil into the insert unit. The pump can be controlled by an appropriate sensor.
Alternatively, the insert unit can be housed at the lowest point in the oil circuit. In this case it replaces the oil pan which has been provided in the prior art for the collection of the oil. If the internal combustion engine is not used, the oil then collects in the insert unit. This has the advantage that, when the insert unit is replaced, most of the old oil can be replaced. In this mode of the invention, all contaminants of the lubricant oil which normally would collect on the bottom of the oil pan remain in the insert unit, and therefore they too are removed. The new insert unit is entirely free of contaminants.
Practical embodiments of the invention are obtained when additional functional elements of the oil circuit are integrated into the insert unit. Examples of such functional elements include the pumps for circulating the lubricant oil and for producing pressure at the lubrication points, as well as an oil deterioration sensor to indicate the need for insert unit replacement, a filter element for cleaning the oil, and/or an oil centrifuge which also can serve for cleaning the oil. Moreover, sensors for the loading of the centrifuge or for wear on the filter medium may be appropriate. The useful lives of the individual functional elements can be coordinated with one another, so that all functional elements will be used up when the filter insert must be replaced. This is especially true for the filter element and the lubricant oil. Of course, functional elements such as the centrifuge and the pump can be matched to the life of the insert unit. They are then supplied together with the filter element and the oil deterioration sensor.
Another possibility, which of course can make sense in the case of the return and refilling of the insert units by the manufacturer, is to design the pump or also the centrifuge for several life cycles of the filter inserts and lubricant oil. These components thus become more expensive, but can be used for a longer time. In particular, the inclusion of the pump or centrifuge creates the possibility of cleaning them when the oil is changed, so that their useful life is longer.
Another possibility is to include a container for oil additives which can be dispensed continuously or at periodic intervals during the life cycle of the oil. These can extend the life of the oil considerably and maintain the required properties of the oil.
In another embodiment of the invention, the insert unit can have additional connections. Thus it is possible on the one hand to achieve a greater branching out of the oil circuit by fastening more connectors to the insert unit, and on the other hand, different kinds of connectors may be necessary for components built into the insert unit; for example, an electrical connection may be provided for the operation of an electric circulation pump integrated into the insert unit.
It is advantageous to provide different identifying marks on insert units of different models, thus avoiding the danger that wrong insert units will be accidentally installed. This is necessary especially when the sizes of the insert unit connectors are the same but oils of different quality are used. For example, insert units for diesel engines might be distinguished from insert units for Otto cycle engines.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either individually or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.